At the beginning of the episode Witless, when they show Johnny talking to the girl whose car he just vandalized, you can clearly see the rear view mirror in both his hand and on the car.
Also, this is the girl's first appearance on the show. She would later play an important role (and also be named) in the episode Candidate Johnny, and have numerous other cameo appearances in various other episodes.
The episode Brave New Johnny marks the first time Johnny travels through time.
(Bus drops Johnny off in Amish Country)
Johnny: Hmm, just like home, only more corn.
(Johnny is using a metal detector to look for loose change, and then starts hitting a car)
Johnny: Whoa mama! This car must be made completely out of loose change! Now to get it into these penny rolls.
(Johnny pushes the penny roll onto the mirror, and the mirror breaks off)
Woman: Excuse me! That's my car!
Johnny: Hey! Finder keepers!
Johnny: (Walking around town with a "Carl is my Best Friend!" sign) Carl is my best friend! He is so smart and nice and a really snappy dresser. I like Carl very much.
(Johnny leans down and talks to a man in a car)
Johnny: Excuse me Mr. motorist, would you run me over with your vehicle. Really, you'd be doing me a favor.
Carl: I don't hear you Johnny.
Johnny: Right. Carl is so great. He is the sun and we are the planets. He has a very pleasant singing voice.
(Johnny talks to a man with a jackhammer)
Johnny: Excuse me Mr. Construction worker, would you please bury me alive. I'll give you a dollar.
Carl: You forgot to mention that I'm an excellent conversationalist.
Johnny: I don't get it Carl. We've been doing this for hours, shouldn't you be dead by now?
Carl: Any minute now. In the mean time, keep proclaiming your devotion to me!
Johnny: Do I have to?
Carl: Oh the tunnel! I see the tunnel!
Johnny: C is for the coolest guy I know! A is for the awful way I treat him!
R is for his really neat bug collection! L is for (Johnny starts crying) the love for humanity! Somebody put me out of my pain!
Carl: Now come here, and be my skating buddy!
Johnny: How long before you die again?
Johnny: What am I doing?! Carl's dying, and here I am pounding his head into the carpet!
Big Brother: No. I kid.
Johnny: You stink! (Audience murmurs) Where's the remote?
Big Brother: You know, buddy, I'd like to say to you what I say to all my critics: SEIZE HIM!
Johnny: Twin sister? How does she looks like?
During Carl be not Proud, when Johnny attempts to get the girl at the ice rink, he says to her if she wants to become part of the Johnny-capades, which is a reference to the ice-capades, a popular ice skating show.
Carl Be Not Proud: - Title
The title of the episode is a reference to John Gunther's 1949 memoir Death Be Not Proud.
Brave New Johnny: - Title and plot
The title of this episode is a reference to Aldous Huxley's 1932 novel Brave New World.
The episode is also a parody of Gorge Orwell's 1949 novel 1984.
Kissing is forbidden in the future:
In Brave New Johnny it's mentioned that in the future, kissing is forbidden. This is a reference to the 1993 science-fiction movie Demolition Man, directed by Marco Brambilla and starring Sylvester Stallone.